Adjust The Atomization; Adjust The Spray Pattern - Graco Merkur 313255F Instructions Manual

Adjust the Atomization

1. Do not turn on atomizing air supply. Fluid pressure
is controlled by the air pressure supplied to the
pump (pump air regulator). Set fluid pressure at low
starting pressure. For low viscosity fluids (less than
25 sec, #2 Zahn cup) with lower percent solids (typi-
cally less than 40%), start at 300 psi (2.1 MPa, 21
bar) at pump outlet. For fluids with higher viscosity
or higher solids content, start at 600 psi (4.2 MPa,
42 bar). Refer to the following example.
Example:
Pump Air
Pump Regulator Setting
Ratio psi (MPa, bar)
15:1 x 20 (0.14, 1.4)
30:1 x 20 (0.14, 1.4)
2. Hold gun perpendicular and approximately
12 inches (304 mm) from surface.
3. Move gun first, then pull gun trigger to spray onto
test paper.
4. Increase fluid pressure in 100 psi (0.7 MPa, 7 bar)
increments, just to the point where a further
increase in fluid pressure does not significantly
improve fluid atomization. Refer to the following
example.
Example:
Pump Air Regulator
Pump Increment
Ratio psi (MPa, bar)
15:1 x 7 (.05, 0.5)
30:1 x 3.3 (0.02, 0.2)
313255F
Approximate
Fluid Pressure
psig (MPa, bar)
= 300 (2.1, 21)
= 600 (4.2, 42)
Incremental
Fluid Pressure
psi (MPa, bar)
= 100 (0.7, 7.0)
= 100 (0.7, 7.0)

Adjust the Spray Pattern

Packages with Airless Guns
The spray tip orifice and spray angle determine pattern
coverage and size. When you need more coverage, use
a larger spray tip rather than increasing fluid pressure.
Align guard horizontally to spray a horizontal pattern.
Align guard vertically to spray a vertical pattern.
Packages with AA Guns
1. See F . 6. Close off pattern adjustment air by turn-
IG
ing knob (AA) clockwise (in) all the way. This sets
gun for its widest pattern.
AA
OUT (narrower
pattern)
F . 6. Pattern Air Knob
IG
2. See F . 7. Set atomizing air pressure at about 5 psi
IG
(0.35 bar, 35 kPa) when triggered. Check spray pat-
tern, then slowly increase air pressure until tails are
completely atomized and pulled into spray pattern.
Do not exceed 100 psi (0.7 MPa, 7 bar) air pressure
to gun.
Operation
AA
IN (wider
pattern)
TI6559A
15